Julia Poska| April 19, 2019

Betsy Stone, contributed photo.

Betsy Stone looks at the very air she breathes every day on a microscopic level.

“Since I started my career here at the University of Iowa, I’ve been amazed at the very interesting air quality events that we’ve been able to study here locally,” the associated professor of chemistry and chemical engineering said.

Her group has researched the environmental impact of a massive tire fire at the Iowa City landfill in 2012 and the ongoing impact of biomass incineration at the University of Iowa Power Plant. Earlier this month, they embarked on a new project to study pollen fragmentation in the local atmosphere.

Stone explained that pollens are fairly large particles and tend to settle out of air quickly. If humans inhale them, they immediately get stuck in the nostrils. Rain events often wash pollen out of air, but in 2013 Stone observed an unusual phenomenon; after thunderstorms, pollens fragmented into much smaller particles and their concentration in the air greatly increased.

Other researchers had observed this phenomenon elsewhere, but never in the Midwest.

“We’re able to follow up with a very heavily instrumented field campaign that we think is going to answer a lot of the burning questions that we have about this type of event,” Stone said.

She’s hoping to learn more about the conditions for fragmentation, the species of pollens present and how they fragment. To do so, the group will use a large suite of equipment—including a meteorological station, an aerosol biosensor, particulate matter monitors and particle samplers—stationed at the university’s cross country course.

Stone said this research has implications for understanding the effects of climate change.

“Part of the reason this research is so important to do right now is that we’re starting to observe changes in our seasons as well as increases in the intensity of thunderstorms,” she explained.

Pollen season is starting earlier, and increased storms mean fragmentation could happen more frequently. Higher temperatures increase pollen loads, too. That’s bad news for people with allergies or asthma, especially since small fragments can travel deeper into the respiratory tract.

Particulate matter can impact the temperature, too. Atmospheric particles can scatter incoming sunlight, creating a cooling effect, but can also absorb energy like greenhouse gases do. Cloud droplets form around particulates, and the quality of the particles impacts the longevity and precipitation cycles of the clouds.

Stone’s group researches more distant phenomena as well, mainly sea spray aerosol collected at Scripps Institution of Oceanography in California.

Ocean bubbles release particles into the air when they burst, which contain both salt and organic matter. Stone’s lab seeks to understand what type of organic matter is present and how it chemically transforms in the sky. This too has implications for understanding climate.

“It’s really important to understand a natural source of particles like the ocean because we have a lot of uncertainty associated with aerosol loadings and composition in preindustrial times,” she said. Thus, our estimates of past climates are not especially accurate.

Understanding natural sources of particulate matter, like pollen and sea spray aerosols, helps provide a baseline to measure climate variation over time. Data on particulate matter can provide a baseline for measuring the success of emission reduction plans and other policies as well, she said.

***This post is part of “CGRER Looks Forward,” a blog series running every other Friday. We aim to introduce readers to some of our members working across a wide breadth of disciplines, to share what the planet’s future looks like from their perspectives and the implications of environmental research in their fields. ***